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New Study Finds the Human Chin Is an Evolutionary Byproduct

Neutrality tests across apes versus humans indicate chin traits show no clear signal of direct selection.

Overview

  • Homo sapiens are alone among primates in having a chin, a trait absent in chimpanzees, Neanderthals, and Denisovans and useful for identifying our species in the fossil record.
  • The research, led by Noreen von Cramon-Taubadel of the University at Buffalo, was published February 12 in PLOS One.
  • Analyses show most chin-specific measures fit a neutral model, even as some other regions of the human skull do exhibit evidence of direct selection.
  • The chin’s appearance is linked to correlated cranial changes, including a shifted cranial angle for larger brains and a reduced lower face with smaller teeth that altered jaw geometry.
  • The authors argue the findings counter adaptationist assumptions and emphasize evaluating skull evolution through integrated trait relationships rather than presumed function.